What conditions have to be met for ImagesCollide ?

What conditions have to be met for ImagesCollide to work?
I want a DummyMouseImage of one pixel to check collision with a number of images.
If I test this in a little testprog. it works fine.
But in my program it doesn't.
Strange thing is; when I change the size of the mouseimage to 5X5 it DOES work.
Now what thing can I have set different, so it doesn't work with the smaller Image?

aah... the problem "in this case" was setscale.
It also scales the Mouseimage when checking for colliding.
pffft.

Can't you use colliderect for checking image-to-mouse?

I'm using Abomination's method too, simply because the docs for CollideRect do not make any sense (the CollideMask and WriteMask params).

[edit] In fact, I'll start a new thread...

CollideRect works similar to CollideImage just with a rect instead of a full image test.

@tonyg: Same as Gfk + I assumed ImagesCollide works the same as in B3D. Well, not quiet. But at least I got it working... so far.
I just wonder what other pitfalls I may encounter?
Would colliderect be a better tool to do the job? No idea how to tackle it...
@Dreamora: I gues we also don't know how CollideImage works. ;)

I just did a speed comparison of ImagesCollide vs CollideRect, and found ImagesCollide appears to be slightly faster anyway.

[edit] Actually, strike that. Been playing with my code for most of the day and CollideRect seems to be significantly faster.

clearly you only need to use images collide if you need pixel perfect collision detection. Depends on the game type as often CollideRect is totally fine.